Gmail – Facebook getting search history from Gmail, LinkedIn and Twitter

Recently, in my Facebook search bar I've noticed it shows "recent searches" that I didn't search on Facebook. For instance, I looked at Paul Graham and Scott Adams' Twitter feeds. This showed up in my Facebook search history:

I've found searches there from

1. Gmail (an email draft I made on my phone)
2. LinkedIn (pages I visited, not searches)
3. Twitter (Also direct page visits)

Are these sites selling Facebook data?

I've got a decently restricted setup:

1. iOS, no Facebook app or Messenger. (However, Facebook login is enabled, with access to my calendar.)
2. I browse on Firefox with NoScript, uMatrix and uBlock origin. I have most things disabled on uMatrix.

How are they doing it, and is there anything further I can do?

Or is it data sales through data gathered by first party scripts?

I'm grateful Facebook is showing this search history from elsewhere so I can see their data sources.